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20

EnS 115 Module 1

By 202380261

Go to stand
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https://covver.com/magazine/202380261/ens-115-module-1
Published
Jul 27, 2026
Pages
29

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  • OverviewIn this course, the basic concepts, methods, and approaches in environmental toxicology will be introduced. Natural and synthetic chemicals commonly encountered in the air, water, and soil will be discussed regarding their occurrence, fate and transport, and toxicological effects on ecological species and humans. Case studies will be used to illustrate the complexity of environmental toxicology issues. New trends in chemical toxicity testing will be discussed. Contaminants of emerging concerns such as pharmaceutical and personal care products and engineered nanomaterials will also be introduced. This module will introduce you to environmental toxicology. Specifically, the topics include the definition and scope of toxicology, brief history of toxicology, dose-response relationships, sources of toxic compounds, and the movement of toxicants in the environment.
  • Learning ObjectivesAfter going through in this module, you should be able to: ➤ define important terms in environmental toxicology;
  • Initial ActivityI want to know if you have any idea/ knowledge about Environmental Toxicology. First, I know that Secondly, I know that Finally, I know that Please write something about this topic: Environmental Toxicology
  • DiscussionI. DEFINITION AND SCOPE A. DEFINITION OF TERMS
  • DiscussionI. DEFINITION AND SCOPE A. DEFINITION OF TERMS
  • DiscussionI. DEFINITION AND SCOPE A. DEFINITION OF TERMS
  • DiscussionI. DEFINITION AND SCOPE A. DEFINITION OF TERMS
  • Target tissueDiscussion I. DEFINITION AND SCOPE
  • DiscussionI. DEFINITION AND SCOPE B. SCOPE OF TOXICOLOGY
  • DiscussionI. DEFINITION AND SCOPE B. SCOPE OF TOXICOLOGY
  • DiscussionI. DEFINITION AND SCOPE B. SCOPE OF TOXICOLOGY
  • DiscussionII. BRIEF HISTORY OF TOXICOLOGY ➤ 1500 BC: The Ebers Papyrus is among the oldest written documentation of medicines in the ancient world. It is the oldest known ancient Egyptian medical scroll, dating back to a period between 1550 and 1500 BC.
  • DiscussionII. BRIEF HISTORY OF TOXICOLOGY ➤ 1939: DDT: Recognized as insecticide by the Swiss scientist Paul Hermann Müller, who was awarded the 1948 Nobel Prize in Physiology and Medicine. Banned in 1972.
  • DiscussionII. BRIEF HISTORY OF TOXICOLOGY Did you know?
  • DiscussionIII. DOSE-RESPONSE RELATIONSHIPS The first recognition of the relationship between the dose of a compound and the response elicited has been attributed to Paracelsus. His statement includes not only that all substances can be toxic at some dose, but that “the right dose differentiates a poison from a remedy," a concept that is the basis for pharmaceutical therapy.
  • Page 17Dose Discussion
  • DiscussionIII. DOSE-RESPONSE RELATIONSHIPS A typical dose-response curve is shown in Figure 3, which plots the relationship between the toxicant dose and the health effects.
  • Threshold DoseDiscussion III. DOSE-RESPONSE RELATIONSHIPS
  • DiscussionIV. SOURCES OF TOXIC COMPOUNDS Everything in the environment is made out of chemicals. These chemicals can either be naturally occurring or synthetic. Both types can be toxic to living organisms; thus natural chemicals can also cause negative effects. Just because they are "natural," does not mean that they are safe.
  • DiscussionV. MOVEMENT OF TOXICANT IN THE ENVIRONMENT Chemicals released into the environment rarely remain in the form, or at the location, of release.
  • DiscussionV. MOVEMENT OF TOXICANT IN THE ENVIRONMENT Lipophilic Toxicants
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT The transport of chemical toxicants can occur through both aquatic and terrestrial food chains, although in the former, higher members of the chains, such as fish, can accumulate large amounts of toxicants directly from the medium.
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT In order for a chemical substance to have any effect, it must first enter the body. Living organisms can ingest them, inhale them, or absorb them through their skin (Figure 7). They may also travel inside the body via mucous in the nose, eye, or ear canals. These pathways are termed routes of exposure.
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT Toxicokinetics
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT Acute toxic effects
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT Categories of Toxic effects
  • DiscussionV. MOVEMENT OF TOXICANTS IN THE ENVIRONMENT Categories of Toxic effects
  • ReferencesCourse References Dekant W. & Vamvakas S. 2004. Toxicology. In Ullmann's Encyclopedia of Industrial Chemistry, (Ed.). https://doi.org/10.1002/14356007.b07_155.pub2
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Discussion

I. DEFINITION AND SCOPE

B. SCOPE OF TOXICOLOGY

1. Modes of Toxic Action

➤ describe an important molecular event in the cascade of events leading from exposure to toxicity.

a. Toxicity at the biochemical and molecular levels

➤ include enzymes that metabolize xenobiotics, generation of reactive intermediates, interaction of xenobiotics or their metabolites with macromolecules, gene expression and signaling pathways. b. Effects of toxicants on animal and human behavior

➤ involves both the peripheral and central nervous systems, as well as effects mediated by other organ systems, such as the endocrine glands.

d. Carcinogenesis c. Effects of diet on the expression of toxicity

➤ includes the chemical, biochemical, and molecular events that lead to the large number of effects on cell growth e. Teratogenesis

➤ includes the chemical, biochemical, and molecular events that lead to deleterious effects on development.

f. Mutagenesis

➤ toxic effects on the genetic material and the inheritance of these effects.

g. Organ toxicity

➤ effects at the level of organ function - neurotoxicity, hepatotoxicity, and nephrotoxicity.

2. Measurement of Toxicants and Toxicity

➤ answer certain critically important questions: Is the substance likely to be toxic? What is its chemical identity? How much of it is present? How can we assay its toxic effect, and what is the minimum level at which this toxic effect can be detected?

➤ Toxicity testing involves the use of living systems to estimate toxic effects. It covers the range of tests (bioassays) from short-term tests for genotoxicity such as the Ames test and cell culture techniques to the use of intact animals for a variety of tests from acute toxicity to lifetime chronic toxicity.